Distributor Rebuild

Complete rebuild of the Autolite or Motorcraft dual-point distributor including points, condenser, cap, rotor, bushing inspection, and advance mechanism cleaning and lubrication.

Warnings

Tools required

Parts

• Distributor points set (dual-point) × 1 — Motorcraft DEC-2 or equivalent
• Condenser × 1 — Motorcraft B7A-12300-A or equivalent
• Distributor cap × 1 — Motorcraft D3AF-12106-AA or equivalent
• Rotor × 1 — Motorcraft D2AZ-12200-A or equivalent
• Distributor shaft bushing (if worn) × 1 — Use OEM specification
• Distributor hold-down clamp bolt × 1 — Replace if damaged
• Distributor advance spring kit (if weak) × 1 — Use OEM specification
• Vacuum advance diaphragm (if defective) × 1 — Motorcraft D2AZ-12370-A or equivalent

Preparation

1. Disconnect negative battery cable
2. Allow engine to cool completely if recently running
3. Clean exterior of distributor and surrounding intake manifold area to prevent dirt entry
4. Remove air cleaner assembly for access
5. Label all spark plug wires with cylinder numbers before removal (firing order 1-5-4-2-6-3-7-8)
6. Photograph or sketch vacuum advance hose routing if multiple vacuum sources present

Procedure

1. 1

   Mark timing reference and remove distributor
   Rotate engine by hand to position number 1 cylinder at top dead center (TDC) on compression stroke. Remove distributor cap and verify rotor points toward number 1 cylinder terminal position. Use white paint marker to mark distributor body position relative to intake manifold, and mark rotor position on distributor body. Disconnect vacuum advance hose. Remove single hold-down clamp bolt and clamp. Carefully lift distributor straight up while noting the rotor rotation as the helical gear disengages (rotor will rotate as gear disengages; mark this final position). Mark this final rotor rest position on the housing.
2. 2

   Disassemble distributor on workbench
   Place distributor on clean workbench. Remove rotor by pulling straight up (press-fit or 2 screws depending on version). Remove 2 screws securing the dust shield and remove shield. Note the orientation of the wire routing clip and point wire positions. Disconnect condenser wire and primary point wires from the point set terminal screws. Remove 2 screws securing the point set. Remove condenser mounting screw and remove condenser. Remove distributor cap if not already removed.
3. 3

   Inspect distributor shaft and bushings
   Grasp distributor shaft and check for radial play (side-to-side movement). Acceptable play is less than 0.006 inches; excessive play indicates worn bushings requiring replacement. Check for vertical end play (should be 0.005-0.025 inches). Inspect cam lobes on distributor shaft for wear, pitting, or grooves. If bushings require replacement, press out old bushings using arbor press and appropriate sized drift punch, then press in new bushings and ream to the Ford-specified shaft-fit dimension (verify exact bushing ID against the service manual for proper shaft fit).
4. 4

   Clean and inspect advance mechanisms
   Inspect centrifugal advance weights and springs for wear or breakage. Weights should move freely without binding. Check springs with spring tension gauge if available; weak springs cause over-advance. Clean all advance mechanism components with solvent and brass brush, removing all old lubricant, rust, and debris. Inspect advance weight pivot pins for wear. Test vacuum advance canister by applying vacuum with hand pump; diaphragm should hold vacuum without leaking. Replace vacuum advance unit if diaphragm is ruptured or leaking.
5. 5

   Install new condenser and points
   Install new condenser and secure with mounting screw. Route condenser wire to point terminal location. Install the point set, securing with 2 screws finger-tight. Connect condenser wire and primary wire to the point terminal screw. Ensure wires are routed clear of moving components and cam lobes. Ensure wires are routed clear of moving components and cam lobes. Apply small amount of distributor cam lube to cam lobes (do not over-apply as excess will contaminate points).
6. 6

   Set primary point gap
   Rotate distributor shaft so cam lobe opens points to maximum gap. Insert 0.025 inch feeler gauge between point contacts. Loosen the point mounting screws slightly and adjust eccentric adjustment screw or shift point base plate until feeler gauge has light drag fit. Tighten mounting screws and recheck gap. Repeat adjustment if gap changed during tightening. Final gap specification is 0.025 inches (0.024-0.026 range) for new points.ion is 0.017 inches for primary points.
7. 7

   Set secondary point gap
   This step does not apply to the single-point distributor used on the 1972 302. Verify the single point set opens and closes properly as the shaft is rotated through a complete revolution, and confirm gap holds at 0.025 inches.fication is 0.017 inches for secondary points. Verify both point sets open and close properly as shaft is rotated through complete revolution.
8. 8

   Lubricate and reassemble distributor
   Apply 2-3 drops of light machine oil to distributor shaft upper bushing area and felt wick (if equipped). Apply small amount of high-temperature bearing grease to centrifugal advance weight pivot points and cam surface under weights. Do not over-lubricate. Install dust shield and secure with 2 screws. Install rotor, aligning tang with slot in shaft. If rotor uses screws, tighten securely. Install new distributor cap, ensuring it seats fully and latches engage properly.
9. 9

   Reinstall distributor in engine
   Verify engine is still at TDC number 1 cylinder compression stroke. Rotate distributor shaft so rotor points to the marked position from Step 1 (accounting for 30-degree counter-clockwise pre-rotation to compensate for gear engagement). Insert distributor into intake manifold, aligning gear with camshaft gear teeth. As distributor drops in and gears mesh, rotor will rotate clockwise approximately 30 degrees to final position pointing at number 1 cylinder terminal. Align distributor body to match paint marks made during removal. Install hold-down clamp and bolt, tightening finger-tight only (distributor must still rotate for timing adjustment).
10. 10

    Install cap and wires
    Verify rotor points to number 1 cylinder terminal position on cap. Install spark plug wires onto distributor cap terminals in correct firing order sequence (1-5-4-2-6-3-7-8, clockwise rotation viewed from above). Ensure wire for cylinder 1 connects to terminal where rotor currently points. Connect all 8 spark plug wires to correct cylinders. Reconnect vacuum advance hose to correct vacuum port. Verify all wires are fully seated and secure.
11. 11

    Set initial timing
    Reconnect battery negative cable. Disconnect and plug vacuum advance hose at distributor. Connect timing light to number 1 spark plug wire per tool instructions. Start engine and allow to reach normal idle speed (approximately 600 RPM in Park/Neutral). Aim timing light at timing marks on harmonic balancer and timing tab. Initial timing specification should be verified from the underhood emissions decal or factory service manual for your specific 1972 302 application (typically 6-10 degrees BTDC depending on configuration). Loosen distributor hold-down clamp bolt and rotate distributor body clockwise to retard timing or counter-clockwise to advance timing until timing marks align at 6 degrees BTDC. Tighten hold-down clamp bolt securely while holding distributor in position. Verified detail (1972 302 initial timing varied by application/emissions calibration (commonly around 6 degrees BTDC but some calibrations differed). Should be confirmed against the underhood emissions decal for this specific vehicle.): Initial timing specification is approximately 6 degrees BTDC for the 1972 302 V8; confirm the exact value against the underhood emissions/tune-up decal for this specific vehicle.
12. 12

    Verify total advance and dwell angle
    With engine idling and vacuum advance disconnected, verify initial timing is stable at 6 degrees BTDC. Gradually increase engine speed to 3000 RPM and observe total advance with timing light. Total mechanical advance should reach approximately 32-36 degrees BTDC at 3000 RPM (26-30 degrees additional advance beyond initial). Reconnect vacuum advance hose and verify timing advances additional 8-12 degrees at idle with vacuum applied. If dwell meter available, verify dwell angle reads 26-30 degrees for the single-point 8-cylinder distributor. Adjust point gap if dwell is outside specification.

Reassembly

1. Reinstall air cleaner assembly
2. Double-check all spark plug wire connections match firing order
3. Verify distributor hold-down clamp is tight and distributor cannot rotate
4. Check for any loose tools or hardware in engine compartment

Verification

• Engine should start immediately and idle smoothly without hesitation or missing
• Timing light should show stable timing at idle with no erratic movement
• Engine should accelerate smoothly without stumbling or backfiring
• Timing should advance progressively with RPM increase and vacuum application
• No arcing or sparking visible around distributor cap or wires in darkness
• Fuel economy and performance should return to normal specifications

More procedures for this vehicle